Thread cutter



May 22, 1945- J; CHUDNER 2,376,417

THREAD CUTTER Filed June '13, 1944 5 Sheets-Shet 1 INVENTOR. L765 e p71/er J. CHUDNER THREAD CUTTER May 22, 1945.

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R m R ||1||i| an "$7 x u J an May 22, 1945. J. CHUDNER THREAD CUTTER 7Filed June 13, 1944 3 Sheets-Sheet 5 NVENTOR. Jseph Chudner' ifnessescase the threads held for continuing anew the- Pat ented Qumran srA'rasPATENT: OFFICE a i useph chuaneai i yt. N. Y. Appl|cati4;nc.::::s13,(1:14.41,1:irl2a;2l;lo-540,127

This invention relates to athread cutting mechanism which may beincorporated advantageously in a sewing machine.

An object of the invention is the provision of a cutting mechanism ofthe indicated character for cutting both the. over thread from the spooland nism as characterized above not only capable of cutting two threads,but capable; of cutting the threads at points close to the sewing orstitching, or if desired beyond the same, to leave end portions of thethreads on the work, and in either stitching or sewing operation.

A further object is the provision of a thread cutter for a sewingmachine which releases the thread tensioning means of the machine priorto cutting the top thread to the needle so as to assure continualsewing.

With the foregoing, other objectsand benefits of the invention willappear when the following Fig. 4 is an enlarged end view of the needlebar and presser foot assembly.

Fig. 5 is an enlarged perspective view of parts ofthe top thread cutterapplied to the presser foot, the latter being raised. a

a of the present in-. venti'on applied thereto. i

cutting members in action cutting the top and bottom threads.

Fig. 12 is a top plan view'of the under-part of the cloth plate togetherwith parts of the bottom thread cutter.

i Fig. 13 is a longitudinal sectional view of parts of the bottom orunder thread cutter in action.

pinching or gripping the thread while cutting it.

, machine-involves parts of the machine as fol- Fig. 6 is a-view partlyin section andpartly in plan of the top thread cutter applied to thepresser foot, the movable cutting member bein shown in its normalposition, the section being taken on the line Hot Fig. 5.

' Fig.7 is a view similar to F18. 6, but showing the aforesaid cuttingmember in its retracted position.

Fig. 8 is an enlarged sectional view taken on the line H of Fig. 6.

Pig. 9 is a iragmentarylongitudihal sectional man u an enlargedsectionalview showingball 21 on its outer'end.

lows: bed in, arm ll, cloth\piate l2, presser toot ll, needle I,needle-bar I5, automatic top thread tension l8, and presser foot lifterThe top or overthread from the spool carried by the pin on the arm II iscut by means which operates in conjunction with the presser foot l3. Thepresser foot is recessed, as at I8, and has a sole plate I! removablysecured to close the recess at the bottom and to provide a cuttingmember'having a cutting edge 20. A movable cut--.

ting memher 2| is mounted on the presser foot in the recess l8 forpivotal or oscillatory move-- ment with respect to the cutting member 9.Ac-

cordin ly, as shown in Figs. 5-9, a pivot 22 on provide a cutting edge25 below and behind the edge 23. An arm "extends radially irom the upperend of the pivot 22 and said arm 26 has a It is to be understood thecutting member 2| moves up and down with the presser foot I: and alsopivots with respect thereto. The .cuting member 2| is only operated whenthe presser foot I! is in he down position. Normally, the cutting me r2| is in the cutting position when the machineis sewing. The top thread28 from the spool 29 passes through the eye of the needle H and extendsdownwardly between the toes or; they presser toot behind the cam surface2| of the. cutting member 2|. As the cutting member 2| pivots to theretracted position the thread'2l is flexed by the camining action of thesurface 24,

thread 28 into the recess l8, thereby'releasably pinching the thread 28between the presser foot and the cutting member 2| and at the same timethe edge 28' coacts with the edge 22 in a shearing action cutting thethread 28 at a point beyond the needle with the thread still passingthrough the'eye of the needle. The thread 28 is therefore severed closeto the stitching or sewing and after the cutting operation the sewingmay be continued anew without any subsequent manipulations.

In order to operate the cutting member 21 for the stated purposes, thereis provided means presently to be described A lever 33 is fulcrumed, 0

turn, thereby causing the operation of the cutting member 2!. The upperend of the lever 3d carries a stud or pin 33. An arm 34 is fixedlyclamped, as at 35, on the forward end of reciprocal rod 36. The arm 3 idepends form the rod 36 and its lower end has a slot 31 which receivesthe pin 33. Upon forward movement of the rod 36, the arm 33 through theintervention of the pin and slot connection 33-31 moves the lever 3b inone direction to retract the cutting member M. The aforesaid pin andslot connection enables raising of the presser foot I3 without upsettingthe operative relationship of the counterparts. The rod 36 is supportedfor reciprocal movement by bearing brackets 38 and 33, respectiv'ely, onthe arm H. A cushion coil spring 40 3 surrounds the rod 36 and has oneend bearing against a head 41 on the rod 38 and its other bearingagainst the bracket '39. A yoke lever 42 straddles the arm II, and isi'ulcruined thereon, as at 43. The head 41 of the rod 38 is connection'44--45. The fulcrum 43 extends transversely through the arm II and hasa radially disposedrod 46 extending downwardly through the bed 10. Aretractile coil spring 41 has one 49 end connected with the rod 46, asat 48, and its opposite end connected, as at 49, with a fixed stud 50 onthe underside of the bed Ill. The control lever 42 has limited movementin opposite.

directions by stops 5| and 52, respectively, on the arm II. The lever 42'is normallyin engagement with the stop 5| under the action of thesprings 40 and 41 with the cutting member 2| in the cutting position.

In order to prevent the mechanism from being operated when the presserfoot is raised, means is provided which cooperates with the presser footlifter l1. Said means consists of a shoulder or the like 53, in thepresent instance formed on the rod '38 by reason of a notch in the rod,as shown 5.",

most clearly in Fig. 5. When the lifter I1 is up for the purpose ofholding the presser foot in the raised position, the shoulder 53 willencounter the lifter I1 and so prevent movement of the rod 38 andparts'connected therewith.

In orderto release the tension of the thread 28 when the presser foot I3is down and at the time the thread is being pinched by the cutting mem'ber 21 just. prior to the thread being cut, means is provided whichoperates in conjunction with 5 the thread tension I6. Said means in thepresent instance consists of a cam surface 54 on the rod 36, as shown inFigs. 3 and 5. The cam surface 34 coacts with a rod 55 incorporated inthe tension 19 in such manner that, as therod 36 moves to cause theactuation of the cutter member 2|, the tension 16 will be operated torelease the thread. Thus, it will be possible for the cutting member 2|to pull the thread 28 into the recess I! to pinch it against thepressure foot 13, subslot 14 and lug 19 enables sumcient th ea be Jectto the withdrawal of the thread upon the movement of the needle 14. Uponthe return movement of the rod 36 to its normal position,

the thread 28 will be automatically placed under tension again.

In order to cut or sever the under or bottom thread 60 from the bobbinsimultaneously with the cutting of the top thread 28, there are pro-.vided means, presently to be described, housed :14 and threads 28 and6B in the usual operation 01 the machine. The part BI is undercut toprovide an inclined surface at the hole 54 whose circular wall embodiedby the part 61! provides a cutting edge 61. The part 62 has elongatedguide grooves or recesses 68 and 69, respectively in the upper and lowersurfaces shown most clearly in Figs. 12 and 13. An elongated steelcutting member 10 is arranged for sliding movement in the recess 58. Themember W'has an upturned transverse cutting edge 11 on the springyforward end. and also has a longitudinal slot 12 to accommodate the feedsurface 13. There is also a slot 14 in the rear end of the member 10 toprovide abutments 15 and 18 respectively. A motion transmission memberand thread puller 11 consisting of an elongated piece of metal isarranged for sliding movement in the recess 69. This part 11 has alongitudinal slot 35 18 which accommodates the feed surface 13. Annected with the lever 42 by a pin and slot conupstanding lug 19 on thepart 11 is received in the slot 14 to cooperate-with the abutments 15 84is adjustably secured to the lever42, with respect to the fulcrum 43, byscrews 86 and slots- 81, respectively, the screw 88 being on the lever42 and the slots 81 being in the throw member 84.

' The member 84 and lever 42 move in unison and cause the operation ofthe bell-crank lever 81.

It will now be understood that when the lever 42 is pushed forwardlythrough the intervention of the member 84 and lever 8.1, the part 11will be slid forwardly from its normal position in which the lug 19 isback away from the abutment 15 in contact with the abutment 16. Theforward movement of the part 11 causes the-front end to pull thethread60 from the bobbin to afford a certain amount of slack. As the part 11continues to be moved forwardly the lug 19 encounters theabutment 15causing the cutting member 1'0 to slide forwardly with the part 11.

the thread 60, and at. the same time cause the member '10 to pinch thethread till against the part 62 of the plate 12. When the lever 42 isreleased, it will'be returned by the springs 40 and 41 against the stop5|, after causing the reverse movement of the part 11 and the cutting.

member 10 in which the lug 19 encounters the abutment 18. The lostmotion afforded by the the sewing anew.

pulled from the bobbin to assure continuance of It isthereforeunderstood that the over thread 28 andthe under thread 60 may be cutsimultaneously close to the sewing or stitching; that suflicient endportions of the threads remain for continuing the sewing anew; and thatthe presser foot may be raised and the threads pulled by hand to leavelong ends on the work before cutting the threads subject to the loweringof the presser foot; that the needle must be raised prior to the threadcutting operation; and that the mechanism can not be operated while thepresser foot is raised and thereby averting damage to parts of themechanism.

I claim:

1. In a thread cutting mechanism for a sewing machine, the combinationof a presser foot. thread cutting means operatively mounted on saidpresser foot, means including a. reciprocal rod for operating thecutting means, a presser root lifter, and means on said rod whichcooperates with said lifter when the latter is in the up position toprevent the cutting means from being operated while the presser foot israised.

2. In. a thread cutting mechanism for a sewing machine, the combinationof thread tensioning means, thread cutting means, means to operate thecutting means including a reciprocal rod having a cam surface, and meansoperated by the cam surface to operate the tensioning means to releasethe tension on the thread prior to thread cutting action.

3. In a thread cutting mechanism for a sewing machine, cooperativecutting members one of which is fixed and the other one being slidable.a

thread pulling member mounted to slide with respect to said slidablecutting member, coactin means on the slidable cutting member and thethread pulling member whereby said thread pulling member may be causedto slide for a part of its travel with respect to the cutting member andthen cause the cutting member to slide with the thread pulling member toperform the following functions, namely, to pull the thread to provide atake-up portion, then pinch said portion, and then sever the threadbeyond the point where it is pinched, and means to slide said threadpulling member in opposite directions.

4. A thread cutting mechanism for a sewin machine comprising cooperativecutting mem bers one of which is movable and the other being fixed, andmeans to operate the movable cutting member, said means including amanually operable rocker on the arm of the machine, a slidable.

rod on said arm, levers on the presser foot of the machine, one of saidlevers being connected with the movable cutting member, the levers beingcooperatively engaged, an arm on one end of said rod, a pin and slotconnection between said arm and the other of said levers, and saidrocker being pivotally connected with the other end of said rod, and aretractile spring acting on said rocker.

5. In a thread cutting mechanism for a sewing machine, the combinationof a presser foot, cooperative cutting members on said presser foot, oneof said cutting members being fixed and the other cutting member beingmovable, a control lever, and means to transmit motion from the controllever to the movable cutting member to operate it, said movable cuttingmember normally disposed in the cutting position at one side of thethread to be cut, and said movable cutting member being so constructedand shaped that it flexes the thread while moving from the cuttingposition to its retracted position and then carries the thread towardthe fixed cutting member to be cut by the cooperative action of thecutting members as the movable cutting member moves into the cuttingposition.

6. In a thread cutting mechanism for a sewing machine; the combinationof a presser foot, cooperative cutting members on said presser foot. oneof said cutting members being fixed and the other cutting member beingmovable. a. control lever, and means to transmit motion from the controllever to the movable cutting member to operate it, said movable cuttingmember substantially crescent shape and .normally disposed at one sideof the thread to be cut so that it flexes the thread while moving fromthe cutting position to its retracted position and then carries thethread toward the fixed cutting member to be cut by the cooperativeaction of the cutting members as themovable cutting member moves intothe cutting position.

ate it, and a presser foot lifter which cooperates with said last meanswhen said litter is in. the

up position to prevent the movement of said control lever.

8. In a thread cutting mechanism as set forth in claim 3, wherein theslidable cutting member consists of an elongated blade with a cuttingedge on one end, and said. coacting means consists of spaced abutmentson the slidable cutting member, and a lug on the thread pulling memberdisposed for movement between said abutments into and out of engagementtherewith in response to the movement of the thread pulling member.

JOSEPH CHUDNER.

